I took about 12 shots of a Christmas tree with lights on it.
First with the flash,the tree lights didnt show up at all.
Without the flash it was dark, so I'm thinking I have to open up the shutter???
I tried the "fireworks" mode on the camera, and that just made burry pics.
Any suggestions for settings in this scene?
ISO, Aperture, White Balance, Shutter speed??

What kind of camera? I would think the fireworks setting would work, so long as you were on a tripod--you were, weren't you? Personally, I'd try starting from this:

Turn off most/all of the lights in the room (night), so the tree lights are providing most/all of the illumination.

Shutter speed/aperture: Start at something like f8 and 2 seconds and go from there. If it's too bright, close the aperture. If too dark, increase the time. Experiment. And of course, use a tripod. If your camera is a dSLR, lock up the mirror and use either a cable release or remote control to avoid any camera shake.

Yep, go for tripod, then automatic should handle it if you just select mode which doesn't use high ISO&noise with shorter shutter speed.
Adjusting exposure might be easier to do with exposure compensation than using manual exposure.

And pressing shutter can equally cause shake so if camera has something like two second timer use it.

First with the flash,the tree lights didnt show up at all.
Without the flash it was dark, so I'm thinking I have to open up the shutter???

I tried the "fireworks" mode on the camera, and that just made burry pics.

Any suggestions for settings in this scene?

ISO, Aperture, White Balance, Shutter speed??

I always have good success with a tripod, the flash turned off, ISO 50 or 100, and then set the shutter speed at 1 sec. or slower. Another good tip is to use the timer button so you don't get camera shake.

The beauty of digital is trial and error, so you can play with the shutter speed until you get it right.

Now, one other very cool technique that I have learned with Christmas photos and especially with lights is to add sparkle (flare brush) effects during post processing in Photoshop. Use the eyedropper tool to select the color of the light and then add a sparkle brush right on TOP of the lights. Very cool effect!

Try it and post a photo for us to see when you are done. Or post a photo and I will be happy to add some sparkle effects in PS if you would like.